Final answer:
Sabeti and Reicht tested for positive selection at the G6PD locus in humans by analyzing the genetic variation in the G6PD gene and comparing it to patterns expected under neutral evolution. Their results showed that specific G6PD variants were more common in areas where malaria is endemic, suggesting that these variants provide a selective advantage against malaria.
Step-by-step explanation:
Sabeti and Reicht tested for positive selection at the G6PD locus in humans by analyzing the genetic variation in the G6PD gene and comparing it to patterns expected under neutral evolution. They looked for evidence of natural selection by examining the frequency distribution of different G6PD variants in populations with a history of malaria.
Their results showed that specific G6PD variants were more common in areas where malaria is endemic, suggesting that these variants provide a selective advantage against malaria. This supports the hypothesis that positive selection has acted on the G6PD gene due to the protective effect against malaria.